JPH11320331A - Thermal deviation correction method of machining tool and machining tool performing thermal deviation compensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of working by storing the relation between the running distance of moving part and the thermal deviation amount therein which are obtained preliminarily, and compensating the thermal deviation in the moving part such as a table or head. SOLUTION: Average working conditions in an actural working is set to vary the running distance of a table 21, and after the thermal deviation at that time is measured, the relation between the two is obtained. The relation therebetween is stored in a storing part of a controller 13. Upon execution of working, the running distance is monitored by the controller 13. By use of the relation between the running distance stored in the storing part and the thermal deviation, estimation of the deviation is carried out, and based thereon, a compensation value is determined. According to the compensation value, feeding of the table 21 can be compensated. Accordingly the feeding error of table 21 caused by the thermal deviation can be reduced, resulting in a wide improvement of the working accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting a thermal displacement in a machine tool.

[0002]

2. Description of the Related Art A machine tool has a main spindle rotating at a high speed and moving parts such as a table and a head. These move as a heat source at the time of machining and cause thermal displacement.

[0003] That is, when the main shaft rotates, it receives heat generated from the bearings and generates thermal displacement.

Further, the table and the head are thermally displaced by friction of a sliding surface due to feeding and heat generated by a ball screw.

Other thermal displacements include a change in accuracy due to a change in room temperature, and a thermal displacement due to heat generated during work processing. However, in the present invention, the above-described thermal displacement related to the sliding of the moving unit is handled.

[0006]

Conventionally, it has been difficult to accurately detect the heat generated by the moving part as the amount of thermal displacement.

In view of the above-mentioned problems of the prior art, the present invention provides a tool for performing thermal displacement correction in a configuration in which the amount of thermal displacement caused by feed of a table or a head is captured by a certain parameter and corrected in software. It is intended to provide a machine and a method thereof.

[0008]

One of the solutions of the present invention is a moving part (2) such as a table or a head of a machine tool.
The correspondence between the travel distance (b) and the thermal displacement (q) in 1) is obtained in advance, the travel distance (b) of the moving unit (21) is monitored, and the thermal displacement (q) is calculated from the correspondence. This is a thermal displacement correction method for a machine tool that estimates and corrects a moving part based on the estimation.

Another solution of the present invention is to provide a machine tool having a moving unit (21) such as a table or a head and a control unit (13) for controlling the moving unit (21) in advance.
The correspondence between the travel distance (b) and the thermal displacement (q) in 1) is obtained and stored in the control unit (13), and the control unit (13)
To monitor the traveling distance (b) of the moving unit (21),
The machine tool is configured to estimate a thermal displacement amount (q) from the correspondence stored in the control unit (13) and correct the moving unit based on the estimated thermal displacement amount (q).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method for correcting thermal displacement of a machine tool according to the present invention, a correspondence (correlation) between a travel distance of a moving part such as a table and a head of a machine tool and a thermal displacement is determined in advance. During processing, the traveling distance of the moving part is monitored, the amount of thermal displacement is estimated from the correspondence, and the moving part is corrected based on the estimated amount.

A machine tool with a thermal displacement correction function according to the present invention comprises:
In a machine tool equipped with a moving unit such as a table or a head and a control unit for controlling the moving unit, the correspondence between the traveling distance of the moving unit and the amount of thermal displacement is obtained in advance and stored in the control unit. Monitoring the traveling distance of the moving unit, and estimating the amount of thermal displacement from the correspondence stored in the control unit,
The configuration is such that the moving unit is corrected based on this.

As the travel distance of the moving section, the product of the ball screw pitch and the number of rotations of the servo motor within a specified time can be used.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual view showing a machine tool having a thermal displacement correcting function according to the present invention.

The machine tool 10 has a base 11, on which a column 12 is formed in a vertical direction. The column 12 includes a control unit 13 for controlling the drive system of the entire machine tool.
Is attached.

On the base 11, a table 21 movable in a predetermined direction is arranged.

The table 21 is driven by a table driving mechanism including a ball screw 23, a ball nut 22, and a servomotor 24.

The ball screw 23 is arranged along the moving direction, and is rotatably supported by a bearing (not shown). The ball nut 22 is fixed to the lower surface of the table 21 and meshes with the ball screw 23. The servo motor 24 is connected to one end of the ball screw 23,
It is controlled by the control unit 13.

In the column 12, a spindle head (head) 14 is disposed so as to be movable in the vertical direction. The moving mechanism includes a ball screw 33, a ball nut 32, and a servo motor 3.
4 and is configured similarly to the moving mechanism of the table 21. The moving mechanism of the spindle head 14 is also controlled by the control unit 13.

A spindle 15 is arranged on the spindle head 14 so as to be able to rotate at a high speed. The spindle 15 is driven by a spindle drive motor 16. The spindle drive motor 16 is also connected to the control unit 13.
Is controlled by

The control unit 13 includes a table 21 described below.
The thermal displacement of the (head 14) is corrected.
In FIG. 1, it is symbolically indicated by a symbol Q.

Hereinafter, a method of correcting thermal displacement will be described with reference to FIG.

The control section 13 has a storage section, and the storage section stores the correspondence (correlation) between the travel distance b of the table 21 (head 14) and the thermal displacement q.

The travel distance b is the ball screw pitch ×
The servo motor speed within the specified time can be adopted.

In order to evaluate the thermal displacement of the table 21 (head 14), the traveling distance b is used as one parameter, and the relationship h between the traveling distance b within a certain fixed time and the thermal displacement q is determined in advance. That is, the average processing conditions in the actual processing are set, the traveling distance b is variously changed, the thermal displacement q at that time is actually measured, and the relationship h between them is obtained in advance.

FIG. 2A shows this state. However, the graph h in the figure is symbolic and does not correspond to actual characteristics.

The relationship h between the traveling distance b and the thermal displacement q obtained in this way is stored in the storage unit of the control unit 13 as described above.

At the time of machining, as shown in FIG. 2B, the control section 13 monitors the traveling distance b of the table 21. Then, using the relationship h between the traveling distance b and the thermal displacement q stored in the storage unit, the thermal displacement q is estimated,
Based on this, a correction value is determined.

The feed of the table 21 can be corrected based on this correction value.

By performing such a correction, a feed error of the table 21 due to thermal displacement can be reduced, and the processing accuracy can be greatly improved.

The thermal displacement correction by the feed of the head (spindle head) 14 can be similarly performed. The thermal displacement of the table 21 and the head 14 may be corrected for only one of them, if necessary.
You can do both.

[0032]

According to the machine tool and the method for performing thermal displacement correction of the present invention, the thermal displacement of a moving part such as a table or a head can be corrected, and the processing accuracy can be greatly improved. Becomes

The present invention is not limited to the above embodiment. For example, the illustrated machine tool is merely an example, and the present invention is applicable to any type of machine tool.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing one embodiment of a machine tool according to the present invention.

FIG. 2 is an explanatory diagram illustrating a method of correcting a thermal displacement amount of a moving unit (table or head) according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Machine tool 13 Control part 14 Spindle head 15 Spindle 16 Drive motor 21 Moving part 22, 32 Ball nut 23, 33 Ball screw 24, 34 Servo motor

Claims (4)

[Claims] 1. The correspondence between the travel distance (b) of a moving unit (21) such as a table and a head of a machine tool and the amount of thermal displacement (q) is determined in advance, and the traveling distance of the moving unit (21) is determined. b) A method for correcting a thermal displacement of a machine tool, which monitors b), estimates a thermal displacement amount (q) from the correspondence, and corrects a moving part based on the estimated thermal displacement. 2. The method according to claim 1, wherein the product of the ball screw pitch and the number of revolutions of the servo motor within a specified time is used as the travel distance (b). 3. A moving unit (2) such as a table or a head.
In a machine tool provided with 1) and a control unit (13) for controlling the same, the traveling distance (b) of the moving unit (21) is determined in advance.
And the control unit (13) stores the correspondence between the distance and the thermal displacement (q), and monitors the traveling distance (b) of the moving unit (21) with the control unit (13). A machine tool configured to estimate the amount of thermal displacement (q) from the correspondence stored in (1) and correct the moving section based on the estimated amount. 4. The method according to claim 3, wherein the product of the ball screw pitch and the number of rotations of the servo motor within a specified time is used as the travel distance (b).